1. Field of the invention
The present invention relates to a digital arithmetic operation unit, and more specifically to an arithmetic operation unit having a bit inversion function capable of executing a given arithmetic operation in a bit-inverted condition.
2. Description of Related Art
In the prior art, a bit inversion arithmetic operation unit capable of executing a given arithmetic operation in a bit-inverted condition comprises an ordinary arithmetic operation unit so constructed that a carry signal is propagated from the least significant bit side to the most significant bit side, and another arithmetic operation unit so constructed that a carry signal is propagated from the most significant bit side to the least significant bit side. A result of operation of one of the two independent arithmetic operation units is selected on the basis of the kind of a required arithmetic operation.
Since the two independent arithmetic operation units are required, the conventional bit-inversion arithmetic operation unit had required a large amount of hardware.